Coping with waterlogged soils will be a challenge for potato growers this spring. Luke Casswell offers tips from the SAC potato conference
Slow drying soils this spring means potato growers may need to reconsider their approach to primary cultivations to avoid causing more damage to land already suffering from the wet season.
What action to take now is a question that many growers have been asking themselves, as the lasting effects of the sodden conditions in 2012 carrying over into this season.
Mark Stalham of Cambridge University Farm’s believes growers need to be careful in not creating more problems this spring with some growers panicking following the wet weather,
“Patience and delaying [cultivations] until conditions are right will be critical,” he told delegates at the SAC Association of Potato Producers Conference near Perth.
“In most cases soil dries very slowly at depth in the spring. So for it to dry at depths of around 40-50cm you would need dry arid conditions which we don’t really have.
“Our spring soils do not dry appreciably below about 20cm and most people cultivate lower than that, meaning most growers will be dealing with soil that is going to be wet,” he said.
Mr Stalham highlighted ploughing as one of the possible solutions to help alleviate the moisture, although admitted many are currently struggling to get on the land.
“If you plough and invert land, it’s obviously a good drying method and that’s why if possible it should be done in these wet conditions. You are inverting dry soil 10in or 12in deep (25-30cm) allowing your wet soil to dry quicker.”
On the heavier land, he believes growers are better off ploughing and cultivating as soon as they can. “The major problems with this though is timing, as everything needs doing at once. So it comes back to your fields having different statuses in terms of drainage, soil, stubble re-growth and understanding these are key.”
Mr Stalham warned the key issue is knowing when to plough, getting this wrong can cause more damage to the land.
“You need to be observant on where you are going to tackle first, and this may involve changing your original plan. The standard maxim of looking at where you’ve got compaction for following crops goes out the window.”
Lessons from last year will be key in dealing with the current season and future seasons. Mr Stalham noted these extreme conditions could continue into the future and growers need to be prepared as best as possible to deal with them.
Looking ahead once primary work is completed, Mr Stalham noted that growers choosing to bed till should go shallower than the de-stoner, with there being no clear benefits to going in at full depth.
Growers will be challenged throughout the season and the need for remedies will come at the wettest times when it’s the most difficult to get on the land, as Mr Stalham explained.
“The time you want to do it is when the soil is at its wettest. You’ve often already done the damage. What you can do is tackle compaction in wheelings. Often the centre of the bed is not the issue, it’s the area with the wheels and that’s where a lot of our waterlogging stems from, when you’ve created an alleyway that will not drain and the water moves sideways.
“Its not just about slopes, its about getting the water to flow into the bed instead of just sitting there or try and move it away completely.”
Early waterlogging in fields will be critical to the physiology of the tubers as this is when most of the damage is done.
Much of that damage is done early on in the season and although there are some remedies to help, Mr Stalham warned that sprays and fertiliser applications can often only offer a false dawn.
“If you think the crop’s not well 50-60 days after emergence, all you’re doing is cosmetically greening the crop and keeping it growing.
“There’s probably far too much nitrogen in late planted crops because there’s a shorter season and more nitrogen will be mineralised naturally because it’s warmer in May/June than in March/April.
So generally you need less nitrogen. You apply nitrogen and the crop perks up and looks greener, but often all you’ve done delay the canopy at this stage,” he said.
See the 9 March issue of Crops magazine for a more detailed look.